Furnace structure



March 19, 1935. Q lP KUENHOLD 1,995,209

FURNACE STRUCTURE INVENTOR ATTORNEY! MM WW2, f77@ ,wp/w

March 19, 1935. o. .1. KUENHOLD FURNACE STRUCTURE F11ed Nov. 14, 1951 2 sheets-Sheet 2 .ww /vf 2/ J f 7./ uw 1 1,3.. awnw/I 1 f 5w@ 9,. d w n M w no,

ATTORNEY,

Patented Mar. 19, 1935 UNITEDA STATES y ,Lausana 1,995,209 FURNACE STRUCTURE Otto J. Kuenhold', ShakerHeights, Oho,.assignor to The Foresty City Foundries Company, Cleveland, Ohio, a corporation of Ohio Application November 14, 1931,v Serial No. 575,003 comms. (o1. 1245+116) My invention relates to an auxiliary warm air heating furnace designed especially for fluid fuel and adapted to be used in conjunction with the usual domestic coal furnace so as to utilize the same air circulating ducts, registers, and the like and, particularly, to aV damper control for such auxiliary furnace.

` lt has been found desirable in auxiliaryfurnaces of the type herinafter described and wherein the vented products of combustion therefrom pass directly into the smoke pipe or flue of the main surface unit, and heated air from the auxiliary furnace passes into the top of the domestic furnace and thence into the circulating ducts, to provide some means for closing off air draft through the-auxiliary furnace combustion products vent to the smoke pipe or flue of the main furnace when the auxiliary furnace is not in use.` That is, it is desirable, when the auxiliary furnace is idle, to cut off all draft communication to the smoke pipe or flue of the main furnace through the auxiliary furnace, and any flow of air, ordinarily heated in the auxiliary furnace and delivered to the circulating ducts and registers through the main furnace, through the 4auxiliary furnace when that furnace is idle.

It is one object of my invention to provide a means for automatically operating the draft dempers and air gates of an auxiliary furnace in accordance with the operation of a fuel supply valve for the combustion chamber thereof in such manner that when the fuel supply'valve is closed the draft dampers and air gate will be closed and, reversely, when the fuel valve is opened the draft dampers and air gate Will be automatically opened.

Another object of my invention is to provide a means for closing off Vthe normal heated airV Fig. l is a sectional view of an auxiliary fur-i nace constructed in accordance with myiinventionl and showing the damper and draft hood air gate and control means therefor; Fig. 2 is a perspective viewof the auxiliary furnace shown in Fig. 1; Fig. 3 is aview of the auxiliary furnace heated'air control gate, showing the gate in closed position; Fig. 4. is a front elevation of a 5 part of the auxiliary furnace. showing the fire door in closed position; and Fig. 5 is a View similar tov Fig. 4 showing the redoor in open position. Y'

Referringy to the drawings, I have shown a fur- 10 nace structure of the type vshown in the copending application, Serial No. 569,433, filed October 17, 1931, for Furnace structure, to which reference may be made for details not herein disclosed or re-V ferred to, comprising a furnace structureA designed to be used in conjunction with a coal furnace of the usual type, and embodying a casing divided into front and back panels 1 and 2, thesepanels being joined aty their meeting edges by interlocking joints or other suitable means so that the side panels 3 and 4 will be readily interchangeable, one for the other, whereby the auxiliary furnace may be erected on either side of a main heating unit .without reversing the auxiliary furnace or .providing additional or different auxiliary furnace parts.k

One of the interchangeable side panels 3 and 4, in this instance,l the panel 4, is provided with an airinlet opening 5 and an air outlet opening 6. A casing top 7 is provided with upwardly extending flanges ending in hook-shaped portions' 8- which hook over the top edge of the furnace casing panels as shownin Fig. Al .to provide a receptacle which may be filled with sand or other heat retardant,l and the casing top preferably slants upwardly toward the air outlet, opening 6 from the opposite sideofthe casing. An upper cover 9 is provided for lending -the casing structure a neat appear-- ance and, at the same time, add an air space for 1 additional heaty insulation. vWith this construction, the auxiliary furnace top 7 may be reversed so as to slant upwardly toward either one side or the other as may be desired.

Each casing panel is provided with an inner lining sheet 10 spaced from the -panelspto provide; an air space for heat insulation, theair spacebeing open at both top and bottom so as toprovide for free circulation between the linings and the outercasing panels. This lining extendsupwardly substantially to the level of the lowest portion of the top vrTand is of the same height at the front,'back', and sides of the casing with the exception of a cut-outV portion in one side vto receivea hotrair flow control gate 32 for controlling the flow of air through the interior burner 13 that is preferably a one-piece cored casing of the main furnace.

driven fan is of a size and operated at a speed of thel auxiliary furnace to the main furnace structure of which it forms a part.

Disposed within the casing just described, is a circulatingV air heating means consisting of a central drum 12 having a burner element 13 therein, and two side drums 14 disposed alongside the Acentral drum. In this instance, there is one drum 14 on each side of the central drum 12 although the number is governed by the conditions which the furnace structure is constructed to meet. The side drums 14 are operatively connected adjacent their tops with the central drumy by means of tubular connecting ducts 15 andthe lowermost ends of the side drums 14 connectwith a U-shaped vent manifold casting 16 that has its central portion projecting rearwardly through the back casing panel 2 as shown in Figs. 1 and 2. The fiow from the side drums 14 is diagonally through the vent casting 16 to a vertical vent duct 17 which gives a method of transferring the vent gases from the side drumsto the vertical vent pipe having the greatest directness and less flow resistance. This vertical vent'duct 17 vents into a draft hood 18 which, in turn, vents through an outlet opening 19 into. the smoke pipe or ue of Ythe'rnain furnace by way of a suitable connecting pipe (not shown).

All of the drums 12 and 14 are preferably supported by the front and back casing panels 1 and 2 and the middle drum 12 is provided withthe casting having ame jets 20 on the top thereof, the casting being symmetrical about its vertical transverse and longitudinal central planes and having supporting lugs 21 at its ends, see Fig. 1. At the rearward end of the burner, the lug 21 fits into a socket 22 while, at the front, the lug 21 fits in a socket 23 that takes the form of an inverted U. Thus, to secure the burner in place, it is first seated in the rear'socket 21 and thence the front end of the burner is moved upwardly until the front burner lug ts in the inverted U` socket 23. A screw 24 projects through a socket supporting casting 25 to hold theburner securely in place. The lugs 21 are preferably rectangular in cross section so as to prevent rotative movement of the burner after the lugs are disposed in the sockets, and a mixer 26 Yis secured to the burner with its outer end `fitting in a recess 27 (see Fig. 4) inthe casting'25. The above described method of securing the burner in place permits the fuel control valve to be screwed into the endof the mixer and fuel pipe connection be made directly thereto without other means f support.

lIn order to have the auxiliary furnace fit any domestic warm air heatingplant,` the 'auxiliary' furnace is arranged to receive its cold air supply from the base of the main furnace through the opening 5 and discharge heated air into the upper part of themain furnace casing through the opening 6. To stimulate the air4 circulation through the auxiliary furnace I provide a motor driven fan 28 of such capacity that it will easily overcome the added resistance to the air fiow brought about by transferring the heated air into the main furnace instead of passing it directly to warm air ducts from the auxiliary furnaceltop but not of great enough capacity to pull the heated air downwardly within the That is,rthe motor in proportion to the warm air exhaust'A capabilities of the main furnace.

As shown in Fig. 2, the motorfan is mounted on a sliding drawer 29 and may be inserted or withdrawn from its desired location through an opening in the cold air transfer duct 30 that leads from the aum'liary furnace to the main furnace. A vertical panel 31 is provided for closing the opening in the transfer duct 30 and is equipped to maintain the entire fan assembly in vertical alignment. y

To control the circulation of air through the auxiliary furnace and into the main furnace in such manner that the auxiliary furnace may be segregated from the main furnace to permit the mainV furnace to be used alone, a hot air gate 32 is provided in the hot air passage 6. This air gate is pivoted as at 33 on a rod extending outwardly from the -side of the auxiliary furnace thermostatic means is provided for partly opening the gate 32, the thermostatic means taking the form of a thermo-metal strip 36 with its free endY disposed between the outer face of the air gate and the hot air outlet 6. Should the hot air gate be in closed position and the burner 13 igynited, the trapped air within the upper end of the casing will heat the thermo-metal strip 36 and cause its free end to bend inwardly toward the center of the auxiliary furnace which will push the air gate 32 outwardly sufficiently for the spring 35 to exert sufficient force on the lever 34 to completely open the gate. This thermostatic gate moving means prevents overheating and possible damage or re.

A gas burner valve 37 of the ordinary tapered plug variety is provided as a burner fuel control means. An arm 38 is secured at the inner end of the plug and a link 39 connects the free end of this arm 38 to an arm 41 that is rigidly mounted on arrock shaft 42 which extends through the rearward side of the auxiliary furnace casing. where an arm 43 is rigidly mounted thereonV (see Fig. 2). With this construction, the arm 43 will move simultaneously and in proportion with movement of the burner valve rotor that is Voperated by a handle 44.

As shown in Figs. 1 and 2, a link 45 is connected to the free endof the arm 43 and extends upwardly thrcughthe vertical draft vent 17 where it ends in a connection with a draft control damper 46 that is pivotally mounted centrally as at 47. This draft damper controls the draft opening and hence the `volume of combustion products allowed to pass to the main furnace smoke pipe or flue. In my construction, another link 43 connects the draft damper 46 with an air gate or damper 49 which is pivotally mounted near one of its ends as at 50, and provides a means for controlling the air in the combustion products that pass from the vertical draft vent 17 to the smoke pipe or flue of the main Vfurnace through the draft hood 18. This last damper Yor air gate provides a check draft regulating means.`

With this construction, damper 46 and damper or air control gate 49 operate simultaneously with the burner .valve rotor and the valve 37 in such'manner that when the burner valve is closed the draft damper 46 and'draft damper or control gate 49 will be in closed position. Reversely, when the burner valve 37 is open, both the draft damper 46 and the draft damper or air gate-'49 will be in open position as shown in Figs. 1 and 2. Likewise, with this construction, the draft damper and damper or air gate will assume positions proportional to the degree of movement of the burner valve.

The burner valve 37 is preferably of such nature that the rotor must be turned Aa substantialY distance` before the fuel passage therethrough is open whereby the damper 46 and damper or air gate 49 will be opened almost half-way before fuelbegins to issue from 'the burner 13. This feature assures suicient damper and aircontrol gate opening whenv the burner is turned on nly part way and the parts may be so adjusted that thedarnper and air control gate are opened proportionate to their needs. This is due to theffact that a larger damper opening relativetovolume of fuel burned is necessary when the burning is at a low combustion rate because of the slower travel of the combustion products.

Thus, turning of the rotor of the valve 37 automatically controls the combustion products `draft openings and hence the volume of combustion products passed into the smoke pipe or iiue of the main furnace is in approximately correct proportion to the amo-unt of gas being burned in the..

auxiliary furnace. This reduces excess of air -in the combustion products passingY to the smoke pipe or flue of the main furnace and hence prevents a large drop in efficiency when the burner valve is turned on only part way. Likewise, the air control gate 49, by reducing the amount of opening to suit the immediate needs, reduces the entrained air in the draft hood 18 when the burner valve is turned o-n only part way whichtends to reduce condensation Vin the smoke pipe of the coal furnace by reducing chilling of the combustion` products iiowing from the auxiliaryA furnace to a point below the dew point which would result from excessive air intermixture. When the burner valve 37 is completely turned olf, both dampers are simultaneously closed with no attention necessary by the operator which prevents escape of hot combustion products present in the drums 12 and 14 as will be hereinafter apparent so that their'contained heat may be passed into the air, if any, which passes through the auxiliary furnace.

Automatic closure of the air control gate 49 when the fuel control valve is turned off to take the furnace out of operation, stops inflow of air through the draft hood18 and into the main furnaceY smoke pipe or fiue which prevents chilling of the vent system during oir periods after the system is under thermostatic control, and prevents checking of the main furnace draft when the auxiliary furnace is not in use. Thus, the draft for the main furnace is not impaired when the main furnace is used alone.

The fact that the draft damper 46 closes simultaneously with the burner valve 37 to prevent escape of the combustion products, makes similar automatic closure of the air control gate 49 and direct venting of the auxiliary furnace into the main furnace smoke pipe or `flue practicable. However, a slight leakage may take place around the draft damper 46 to have it practical for a stand by pilot burner to be provided in the auxiliary furnace, and the parts-are so constructed and located that, should` the operating mechanism break, the ,dampers will gravitate to open position. This is an additional safetyfeature.- Y

The air control gate Y49, shown inits extreme open positionalso acts as a downv draft baiiie yto preventV downward drafts through the main'pipe or flue from reaching the outlet of the vertical Vent ductnl'l. This air gate with the open bottom khood lforms a' rectangular shapeddraft hood havingA well known functions .but with the added feature of having a closable outlet. This is vaccomplished by combining air control gate or baffle in Yone member.

As hereinbefore stated, .a single gas valve is provided and, for convenient lighting, the burner islocated immediatelyinside a fire door 50 with the burner top level with the bottom ofthe fire door.' Ordinarily, an operator is inclined to turn on full fuel supply when lighting the burner which results in the flame flaring out through the fire door. Therefore, means/is provided which makes ,it impossible to .turn on the rfull fuel supply While the fire door 50 is open. As shown in Figs; 4 and5, thismeans consists of a bell crank 51 pivoted at some point on the burner valve rotor withl a link 52connecting one end ofthe bell crank with the fire door 50, the connection being located at the proper distance from thehinge axis of the door to provide a lever which, when the iire door 50 is opened, moves the bell crank 51 about its axis by means of the connecting link 52.` The bell crank is so arranged that one arm 53 thereof will, when the rerdoor 50 is opened, moveso that it interferes with-and preventsfull movement of the arm 41 as shown in Fig. 5, the arm 41 being connected to the burner valve rotor as hereinbefore describedand being -actuated by turning of the rotor.

Inmy preferred construction, the arm 41 is provided withl a projecting lugY 54 in which a screw is so located that it will Astrike the end of the bell crank arm 53 when the re door 50 is i burner valve until movement of the arm 41 and l the burner valve is stopped .by interference with the lug 54 on the arm 41. Then, as the re door is closed, the Valve rotor may be turned to l complete on position as shown in Fig. 4. Further, this adiustment may be such that the burner valve may be opened just sufficiently for proper ignition of the burner 13 without having the flame from the burner flare out at the open rer door,with, as before, complete opening of the fuel Valve prevented until the fire door is'closed. Such construction compels a safe and proper ignition of the burner and the construction may be varied so long as a means is provided for interfering with full burner Valve opening until the fire door 50 is closed.

In the operation of this auxiliary furnace, air for combustion enters the space 13 below the burner and passes upwardly around the burner 13, lit being understood thatfuel issuing from the burner has previously been ignited and the draft dampers are in open position. Combustion products from'the burner 13 passupwardly drums, with the amount and speed of downward flow in the two or more side drums tending to balance. That is, if one sidedrum loses more heat than the other, more products of combustion gravitate through it and the temperature of the burned gases at any given level are substantially alike in both side drums and are of progressively lower temperatures at lower levels.

When the combustion products are sufliciently cool to reach the bottom of the side drums 14, they pass from the rear ends of the side drums into the vent manifold casting 16, thence upwardly through the vertical vent passage which vents into the open draft hood 24, and thence through an outlet opening 19` into a vent pipe that leads .to the smoke pipe .or flue of the main furnace.V With this construction, it will be seen that the damper 46 and the damper or air control gate 49 control the passage of combustion products 4from the auxiliary furnace to the smoke pipe or nue of the main furnace as hereinbefore described. v

The downward circulation of products of combustion'in the side drums is due mostly to gravity and this free circulation of combustion products through the furnace make it possible to employ a rear vent passage 1'? of very small size,`hence Vthe draft hood land vent outlet 19 may below in elevation. This is important in iii) auxiliary furnace structures because it is desirable to Vent the passage directly into the smoke pipe or flue of the main `heating unit which eliminates the need of a separate vent pipe. The freedom of draft secured within the furnace makes'possible a low rear vent connection capable of being connected to the smoke pipe Vwith an upward pitch betwen the draft hood and the smoke pipe, and `also gives a rapid pick-up of the draft when the burner is started at full capacity. Y i

The circulation of theair to be heated in the auxiliary furnace, which air passes into the furnace through the inlet opening 5, is in an upward direction between the drums 12 and 14, the air being drawn inwardly by the fan structure hereinbefore described and forced outwardly past the air gate 32 through the voutlet 6 and into the top of the main heating -unit or furnace structure. Justbefore the combustion products leave the side drums, they are exposed to the greatest heat extracting or cooling influence possible, that is, that of the incoming air.

The airaround the side drums flows in a direction opposite to that of the combustion products within'the side drums which results in progressively greater heating inuence upon the air as it travels upwardly, and progressively greater cooling inuence upon the combustion products as they travel downwardly. Just before the airV reaches the hot air outlet 6, it is exposed to the influence of the hottest heating surface with the result that the greatest average temperature difference exists between 'the heating surface and the air which it is possible to achieve on a practical basis. This, in turn, results in the greatest possible heat transfer-'per 'square lunit of the heating surface and such direct and practically unimpeded upward flow of the air to be heated provides a strong air circulation which is a very desirable feature in an auxiliary'furnace.

With the control for the flow of-combustion products and control of the now of air through the auxiliary'furnace abovefdescribed, it is possiauxiliary furnace alone or use them simultaneously and in combination. In using the main heating unit alone, the control means which I have provided permits the flow of air through the combustion products exhaust to be entirely cut off whereby, with an auxiliary furnace Venting Vmakes it possible to entirely segregate the auxiliary furnace fro-m the main heating unit. It is Valso possible, by the use of the force draft means including the fan, to use the auxiliary heating unit separately from the main heating unit since the forced draft means is of a size to deliver air to the auxiliary furnace in proportion to the amount of air it is possible for the circulating ducts and registers to deliver and very little, if any, unheated air will pass directly upwardly'to the circulating ducts through the main heating unit. In using the auxiliary furnace alone, no change is made in the main heating unit inasmuch as the flow of heated air is upward and directed into the main heating unit at substantially the point at which heated air is removed from the main heating unit to be delivered to the room register or other equipment. The safety features provided by the damper and air gate 'control permit the auxiliary furnace to be segregated from the main heating unit without fear ofeffect on the operation of the main heating unit.

What I claim is:

l. A, warm air furnace, comprising a casing, an air heating means including a` burner element in said casing, a fuel supply for said burner element,

v a valve for controlling said fuel supply, a combustion products vent passage, an air draft hood in association with said vent passage, a damper in said vent passage, an air control gate in said hood, a connection between said damper and said 4air control gate, and a connection between said damper and said fuel supply valve, whereby actuation of said valve Vwill cause proportionate movement of said damper and said air control gate.

ZJA warm air furnace, comprising a casing, an air heating means including a burner element in said casing, a fuel supply for said burner element, a valve for controlling said fuel supply, a combustion products vent passage, an air draft hood in association therewith, an air control gate in said air draft hood, and a connection between said air control gate and said fuel supply valve, whereby actuation of said fuel supply valve will cause proportionate movement of said air control gate. Y

3. A warm air furnace, comprising a casing, an air heating means including a burner element in said casing, a fuel supply for said burner element, a valve for controlling said fuel supply, a combustion products vent passage, an air draft hood in association therewith, a combined air control gate and baffle in saidair draft hood, and a connection between said air control gate and said fuel supply valve, whereby actuation of said fuel supply valve will cause proportionate movement of said air control gate.

4. In a furnace structure having a combustion chamber and a combustion products vent pipe leading therefrom, an open bottom draft hood into which the delivery end of said vent pipe extends, said drafthood being connectable at its top to a chimney, means in said draft hoodV- for deecting down draft air through said hood away from the delivery end of said vent pipe, said deiiector being movable to cut off communication between said draft hood and said chimney, a damper in said vent pipe effective to control the passage of combustion products therethrough, and a connection between said damper and said draft hood deflecting means whereby they operate in unison.

5. In a furnace structure having a combustion chamber, a burner element and a combustion products vent pipe leading from said combustion chamber, an open bottom draft hood into which the delivery end of said vent pipe extends, said draft hood being connectable at its top to a chimney, means in said draft hood for deecting down draft air through said draft hood away from the delivery end of said vent pipe, said defiecting means being movable to'cut off communication between said 'draft hood and said chimney,

a fuel supply valve for said burner element, and

a connection between said deecting means and said valve whereby operation of said valve will produce proportionate movement of said deecting means.

6. In a furnace structure having a combustion chamber and a combustion products vent pipe leading therefrom, an open bottom draft hood into which the delivery end of said vent pipe extends, the delivery end of said vent pipe being of less cross-sectional size than the open lower end of said draft hood, whereby an air passageway is provided therebetween, said draft hood OTTO VJ. KUE'NHOLD.: 20 

